▎ 摘　　要

This study demonstrates that ligand-modified graphene quantum dots (GQDs) facilitate the simultaneous operation of multiple tasks without the need for external dyes. These tasks include selective cell labeling, targeted drug delivery, and real-time monitoring of cellular uptake. Folic acid (FA)-conjugated GQDs are synthesized and utilized to load the antitumor drug doxorubicin (DOX). The fabricated nanoassembly can unambiguously discriminate cancer cells from normal cells and efficiently deliver the drug to targeted cells. The inherent stable fluorescence of GQDs enables real-time monitoring of the cellular uptake of the DOX-GQD-FA nanoassembly and the consequent release of drugs. The nanoassembly is specifically internalized rapidly by HeLa cells via receptor-mediated endocytosis, whereas DOX release and accumulation are prolonged. In vitro toxicity data suggest that the DOX-GQD-FA nanoassembly can target HeLa cells differentially and efficiently while exhibiting significantly reduced cytotoxicity to non-target cells. (C) 2014 Elsevier B.V. All rights reserved.